This invention relates to a bone marrow extraction tool. More specifically, the invention relates to such a tool having means to separate the marrow sample from the marrow mass while the distal end of the tool is buried in the mass.
There has been a need in bone marrow biopsy tools for improved means for severing the biopsy sample from the marrow mass. The prior art U.S. Pat. No. 5,807,277 to Swaim discloses relative rotation of inner and outer cannulas to cut off the sample, each cannula having a curving beveled nose. The present invention makes such relative rotation unnecessary.
The invention is a bone marrow extraction tool which comprises an outer cannula having an interiorly and exteriorly tapered marrow-receiving open distal end, and an inner cannula slidably disposed in the outer cannula and having a distal end formed with longitudinal slots. The slots define resilient sectors. The mouth of the inner cannula is adapted, when forcibly engaging the interior taper of the outer cannula to diminish in diameter as the sectors flex inward. The ends of the sectors compress marrow disposed in the mouth and squeeze it off from the marrow mass outside the outer cannula.